SN04-N NPN Metal Detection Proximity Sensor 5mm DC 10-30V

The SN04-N Inductive Proximity Sensor is a compact and durable non-contact metal detection switch widely used in industrial automation, robotics, and CNC systems. It detects metallic objects using an electromagnetic field and provides a reliable digital NPN normally-open output.

Designed for harsh environments, this sensor features high accuracy, fast response, and strong resistance to dust, vibration, water, and oil, making it suitable for both industrial and DIY applications.

Key Features

• Inductive Metal Detection: Detects metal objects only (iron, steel, etc.) without physical contact
• Detection Range: Up to 4–5mm sensing distance (depends on metal type and size)
• Wide Voltage Range: Operates on 10V to 30V DC
• NPN Output (NO): Normally Open digital output for easy interfacing
• LED Indicator: Built-in LED shows detection status
• High Durability: Resistant to dust, oil, water, and vibration
• Fast Response: Suitable for high-speed industrial sensing

Technical Specifications

• Model: SN04-N
• Sensor Type: Inductive Proximity Sensor
• Operating Voltage: 10V – 30V DC
• Detection Distance: 4–5mm (typical)
• Output Type: NPN, Normally Open (NO)
• Current Consumption: ~5mA
• Output Current: Up to 150–200mA (typical max)
• Response Frequency: Up to ~500Hz
• Indicator: Red LED
• Housing Material: ABS plastic
• Cable Length: ~1 meter
• Protection: Reverse polarity & short-circuit protection

Working Principle

The sensor generates an electromagnetic field at its sensing face. When a metal object enters this field:

• Eddy currents are induced in the metal
• Sensor detects the change in field
• Output switches ON (NPN sinks to ground)

This enables contactless and wear-free detection, ideal for repetitive operations.

Wire Configuration

• Brown → VCC (+10V to 30V)
• Blue → GND (0V)
• Black → Output Signal (NPN)

Applications

• Industrial automation systems
• CNC machines and 3D printers (endstop / bed leveling)
• Conveyor belt object detection
• Robotics and motion control
• Limit switch replacement
• Metal sorting and detection systems

Advantages

• No mechanical wear (long lifespan)
• High reliability in industrial environments
• Stable and repeatable detection
• Easy integration with PLCs and controllers

Usage Tips

• Only detects metal objects, not plastic or wood
• Detection distance varies with metal type (iron > aluminum > copper)
• Use a pull-up resistor when connecting to microcontrollers
• For Arduino/ESP32, use a voltage divider or optocoupler (since output may be higher than 5V logic)

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